Key signature error correction

see topic :
http://musescore.org/en/node/22887
[[nodetitle:Key signature change problems]]

I think this discussion is about the possibility to correct a chosen key signature after input of notes. Now musescore reads the underlying data input (notes, like G#) and the key signature and combines this to the score on screen.
Is it possible to let the user draw notes and key signature (on screen) and let musescore interpret this to the notes after the user gives a certain command ? The user is then free to draw what he/she wants and let the program translate it to the actual notes.
Is the following an idea to implement a key signature error correction?
I think (correct me if I'm wrong) it is easy to let musescore strip out all the flats and sharps of the input and save it in say, data2, show that on screen, let the user choose a key signature and let musescore add the sharps and flats to data2 and save it to data3. Data3 are the (real) midi notes after that.
Thanks,
Jan